ML20248J946
| ML20248J946 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 05/29/1998 |
| From: | Muench R WOLF CREEK NUCLEAR OPERATING CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| ET-98-0044, ET-98-44, NUDOCS 9806090370 | |
| Download: ML20248J946 (3) | |
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I Wt!) NUCLEAR OPERA
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LF CREEK l
Richard A. Muench Vice President Engineenng klAY 2 91993 ET 98-0044 U. S. Nuclear Regulatory Commission ATTN:
Document Control Desk Mail Station: Pl-137 Washington, D. C.
20555 l
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Subject:
Docket No. 50-482:
Additional Information to Support the Maintenance Rule Inspection at Wolf Creek Generating Station l
Gentlemen:
At the conclusion of the NRC Maintenance Rule baseline inspection at Wolf Creek Generating Station, conducted April 20 through April 24, 1998, Wolf Creek Nuclear Operation Corporation (WCNOC) agreed to provide additional information regarding the failure to identify functional failures on the Main Steam System.
In addition, WCNOC is providing information on the inspection item related to the performance of the Periodic Assessment of Maintenance Effectiveness as required by 10 CFR 50.65 (a) (3).
This additional information is provided in the attachment, If you have any questions concerning this matter, please contact me at l
(316) 364-8831, extension 4034, or Mr. Michael J. Angus at extension 4077 l
Very truly yours, f.dE4 l
Richar A. Muench RAM /rlr Attachment ec:
W.
D. Johnson (NRC), w/a E.
W. Merschoff (NRC), w/a J.
F. Ringwald (NRC), w/a K. M. Thomas (NRC), w/a J. E. Whittemore (NRC), w/a 9806090370 980529 PDR ADOCK 05000482 G
PDR L,,(
P.O. Box 411/ Burhngton, KS 66839 / Phone: (316) 364-8831
'5 An Equal Opportunny Employer M/FiHC/ VET
Attachment to ET 98-0044 j
Page 1 of 2 Additional Information to Support the Maintenance Rule Inspection at Wolf Creek Generating Station I
o Main Steam' System During a review of information in the Wolf Creek Nuclear Operating Corporation (WCNOC) Maintenance Rule database regarding the Main Steam System, the inspector identified that failures of an Atmospheric Relief Valve (ARV) on May 5,
1995, (Valve ABPV002) and on April 20,
- 1996, (Valve ABPV003) were not categorized as functional failures for the Main Steam System function to provide Reactor Coolant System (RCS) cooldown.
The inspector believed that these individual failures should have been classified as functional failures, which would subsequently result in exceeding reliability criteria for this function.
The Main Steam System function to provide RCS cooldown states: " Achieve a 50
)
degree per hour cooldown rate through the atmospheric relief valves or through the condenser steam dump valves."
The Plant Safety Analysis (PSA) supports successful accomplishment of RCS cooldown through the use of only two of four main steam loops through the ARV.
Because of the PSA results and the basis for Technical Specification
- 3. 7.1. 6, which allows a single ARV to not be available for cooldown, the failure of a single ARV is not considered a j
functional failure when monitoring at the system level.
If WCNOC had chosen i
to monitor this system function on a train basis, different reliability criteria would have been established.
Because of the PSA results for single ARV failures and the associated affect on the ability to cool down the RCS, it is expected that a number greater than one failure would have been established for the reliability criteria.
As indicated during the initial Maintenance Rule presentation to the inspection team, a scope val.idation effort was undertaken based on conflicts identified in the Maintenance Rule Program documentation (reference Performance Improvement Requests (PIR) 97-0771 and 97-0204, which were included in the information provided to the inspection team prior to the inspection).
The reliability criteria for the above function is listed in the currently approved scope, as audited by the inspection team, as "No more than 1 failure of code safeties, ARVs, supply valves to TDAFWP, and/or Main Steam 1 solation Valves to respond to demand in 18 months."
Not all of the listed types of valves directly support the subject function.
Because of this confusing information, this subsequently became one example of the need to validate the complete Maintenance Rule scope.
The Main Steam System function to provide RCS cooldown remains in the proposed scope of the Maintenance Rule; however, revised reliability criteria is being developed.
WCNOC concurs that the Main Steam System should have been classified as (a) (1) during initial implementation of the Maintenance Rule l
based on the reliability criteria wording currently contained in the WCNOC l
The reliability criteria of this function specifically refers to the failure of an ARV to respond to demand in 18 months, without specific consideration to the loss of the system function.
During the inspection, the Main Steam System was placed in (a) (1) until these failures could be reviewed further.
The application of proper performance criteria is one item that is reviewed when evaluating the root cause for exceeding performance criteria, as described by the guidance contained in NUMARC 93-01,
" Industry Guideline for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants."
WCNOC will review this performance criteria for potential changes as part of the root cause and corrective action determination.
l e-__-_-__-________.
Attachment to ET 98-0044 Page 2 of 2 Additional Information to Support the Maintenance Rule Inspection at Wolf Creek Generating Station Periodic Assessment of Maintenance Effectiveness:
During a review for compliance with paragraph (a)(3) of 10 CFR 50.65, the inspector was informed that WCNOC had not yet completed the Periodic Assessment c'f Maintenor'ce Ef festiveness for fuel cycle 9, which had ended at the completion of the 9th refueling outage on December 1,
1997.
This assessment had not _ been completed based on the wording of the rule that states: " Performance and condition monitoring activities and associated goals and preventive maintenance activities shall be evaluated at least every refueling cycle provided the interval between evaluations does not exceed 24 months."
WCNOC understood the regulation to allow evaluation for fuel cycle 9 to be completed no later than July 10, 1998, which corresponds to 24 months from implementation of the rule since the time between evaluations could not be L
established otherwise.
WCNOC' s interpretation of paragraph (a) (3) with no supporting information in the Statements of Consideration, led WCNOC to schedule the evaluation in the Spring of 1998, believing that this was allowed by the regulation.
No information contained in the regulation would indicate that the evaluation shall strictly be completed within a lesser time frame.
The evaluation of fuel cycle 9 had originally been intended to be performed in January 1998 (approximately two months following the 9th refueling outage).
However, this evaluation was deferred based on previously initiated corrective actions and a need to fully understand the status of the Maintenance Rule Program through performance of a self assessment.
Objectives of this self assessment included an evaluation of the overall WCNOC Maintenance Rule program implementation and its effectiveness in meeting the objectives of the Maintenance Rule.
Completion of the self assessment prior to the periodic assessment of maintenance effectiveness, required by paragraph (a)t3), has proven beneficial. The self assessment heightened our understanding of the Maintenance Rule Program deficiencies / weaknesses.
The information provided by 1
our self assessment will significantly enhance the Periodic Assessment of Maintenance Effectiveness.
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